Despite considerable effort and characterization, the precise role of PKA in regulating sperm development and the acquisition of motility and fertilization competence remains unclear. A major roadblock in these studies has been the lack of techniques to manipulate the expression and activity of PKA in sperm cells since no readily accessible cell culture model is available that allows address questions that related to the importance of subcellular localization, PKA activation state, and developmental changes in survival of spermatids (2) Determine the role of C subunit during spermatogenesis (3) Examine the anchoring of RI and its physiological significance during spermatogenesis (4) Identify specific PKA substrates in sperm and develop a mechanism to inhibit sperm PKA in vivo. These studies are relevant to larger questions concerning the treatment of infertility and the development of male-specific contraceptive approaches.